This invention relates in general to a mass transfer or distillation column and, more particularly, to structure within the column for concurrently contacting a fluid stream with a particulate solid catalyst while distilling the reaction product, as well as downcomer structure not restricted to catalytic applications.
Conventional structures for carrying out catalytic reactions within distillation columns generally comprise containers which are filled with catalyst and are arranged within the column to concurrently serve as a catalytic and distillation structure. The catalytic chemical reaction zones are thus combined with the mass transfer zones in these types of structures, for controlling the quantity of fluid entering the mass transfer zones.
Another limitation of known structures which allow concurrent reaction with distillation is the difficulty encountered in replacing the catalyst when it is spent. To renew the catalyst, the internal structure must be removed from the reactor shell, reloaded with catalyst and repositioned in the reactor. At best, this is a time consuming and labor intensive procedure. The catalyst in some types of prior art structures is maintained in cloth belts which are joined with a steel wire support structure. Replacement of the catalyst in these structures requires removal and renewal of both the support structure and the catalyst belt. Significant losses in operating time of the column thus result from renewal of the catalyst, especially when catalysts which have a cycle life as short as several months are utilized.
Conventional downcomers used in conjunction with trays in distillation columns have been solid wall structures. The capacity of such a downcomer to transport liquid between trays is limited by the open cross-sectional area of the device.